I don't know if I have seen anyone here have their CYA that high! , Then again I've only found this wonderful place last April...

Chuck

OK, first round of water change is about done. I think I got about 25% drained and refilled. A very slow process.

Probably a question that has been asked before...but does anybody make pucks that don't have CYA in it?

Yes, there are Cal-Hypo tabs, but they tend to fall apart quickly as they get smaller and have gummy fillers for binders and they need special feeders since they dissolve more quickly than Trichlor tabs/pucks. Though they do not increase CYA, they increase CH. Unfortunately, there are no slow-dissolving forms of chlorine that do not increase CYA nor CH.

Well, I've completed two partial water changes, which I estimate to be about 60% of my total pool volume. Here are my new results:

FC .5
CC 1
TC 1.5
pH 7.1
TA 120
CH 350
CYA 100 (diluted test)
Temp 66

Based on my new test results, it appears I have probably only changed about 50% of the water. I won't be able to do any more water changes until Monday night, as I'm about to leave on a business trip. Oh well, at least I'm headed in the right direction with all this!

Put some chlorine in your pool before you go.....about 12ppm or so. Your water is easily warm enough to support algae growth.

Hello all, I'm back, with more info:

After a three day absence, I came back to town last night and completed my fourth @ 30% water change. Put some bleach in after the refill last night, and here are the readings I just took tonight:

FC 17
CC 1
TC 18
pH 7.5
TA 140
CH 300
CYA 75
Temp 66

The CYA is coming down, but very stubbornly. Seems strange that TA is increasing with every water change? I'm pleased that my pH has come up, and the CH is coming down. I am still attacking with chlorine even though I have been doing water changes. I was surprised to see so much FC still in my pool, 24 hours after adding it. Normally it would be all gone by now.

What I am most pleased about is that the filter pressure is not rising quickly like it was before (I cleaned it on Saturday). It has only risen 3 psi since then. Normally, by now it would be 18 psi and the flow would be pitiful.

Should I finish the shock process and then do another water change to try to take the CYA down yet again?

Thanks everybody.

With that much FC I am suprised to see any cc after 24 hours... looks like you need to continue shocking.

That's an indicator that you are killing the organics (algae) in your pool so the FC is not consumed so fast. You don't say what FC you started with prior to your abasence so it is difficult to assess your situation accurately.

Always dose and test all your chemistry accurately so you can see what changes have occured.

i.e, if you started with FC 18 and now have FC 17 that's good. If you started with FC 45 and FC now 17 that's a different scenario.

As Lershac indicates, I would continue the shock process until cc's are .5 or less and you lose not more than 1ppm FC overnight. Then the process will be complete and you can do your drain and refill to get CYA down some more.

Last night, I added enough bleach to bring my FC up to 21.
Tonight, the FC was at 20, CC at .5.

I will wake up extra early tomorrow morning for the OCLT test, hoping to see that I haven't lost any more than 1 ppm of FC.
I think I can see the finish line.

I'll say one thing, when you get thru all this I'll bet your gonna keep that pool water sparkling
Any pictures of your pool?

Got up at the crack, even pre-crack this morning.
FC was down to 17; CC was close to zero.
Added more bleach to bring it up to the shock level of 21. Will test and attempt the OCLT again tonight/tomorrow morning.
The water looks as good as I've ever seen it. The filter pressure no longer increases daily.
I will attach some pictures this weekend!

Nice work, Mike. It looks like you are in the home stretch of getting your pool back the way it should be.

Hi Mike,
What is a latest CYA test?
The last I see that you have posted is 75.
If your shocking about 20-21 ppm chlorine, you need to be about 50 ppm on your CYA.
In my case, I was at work for long days and my chlorine was falling below my shock value by the time I would get home.
One of the moderators suggested I go over my shock value # by 3-4 ppm, so I would never fall below my chart shock level during the day.
My pool passed OCLT in a few days after I started doing that.

Chuck

Hi Chuck:

Hmmm...The Pool Calculator tells me that the shock value for my pool with all the last test data, including CYA of 75, is 21.

I haven't tested my CYA since the last water change, a couple of days ago. I thought that it would not come down any further unless I continued to change the water, so I just left it where it was so I could attack the algae.

Maybe I read something wrong, somewhere. I will test for CYA again tonight, before I go to bed.

Thanks,

No need. You are correct, unless you drain or add water CYA will stay virtually constant in your pool for at least a month or so.

Well, I think I've finally passed the OCLT test!
Last night, my FC was 22 and CC was <.5.
This morning, the readings were exactly the same.

Tonight, I will brush the entire pool again.
Tomorrow, I will clean the filter, and then do another partial water change to bring the CYA down to about 50, I hope.
After that, I hope to just "keep up" with the bleach!

Thanks everybody!

Ok, I was using the pool school chart here for my pool:
pool-school/chlorine_cya_chart_shock

Great news to hear you passed the OCLT!

Chuck

Thanks, Chuck.

Yep, I see what you mean. I wonder why that chart is different than what comes out of the Pool Calculator? I though it all came from chemgeek anyway?

It actually all originates with Ben Powell, who operates another pool site. My understanding is that Richard (Chem Geek) refined it into what essentially became the CYA chart, and Jason (JasonLion) used slightly different values for the calculator.